Building block



FIG. 1 is a top perspective of a first embodiment of a building block of the present invention;

FIG. 2 is a bottom perspective view thereof;

FIG. 3 is a bottom view thereof;

FIG. 4 is a top view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a left side view thereof;

FIG. 7 is a front view thereof;

FIG. 8 is a rear view thereof;

FIG. 9 is a top perspective of a second embodiment of a building block of the present invention;

FIG. 10 is a bottom perspective view thereof;

FIG. 11 is a bottom view thereof;

FIG. 12 is a top view thereof;

FIG. 13 is a right side view thereof;

FIG. 14 is a left side view thereof;

FIG. 15 is a front view thereof; and,

FIG. 16 is a rear view thereof. 

CLAIM The ornamental design for a building block, as shown and described. 